Pub Date : 2023-11-15DOI: 10.23919/SAIEE.2023.10319379
Paula Akossiwa Atchike;Jamal Zbitou;Ahmed El Oualkadi;Pascal Dherbécourt
Electronic devices with high performances like Power Amplifiers (PA) are very important for Wireless communications. This paper proposes a design of a class AB power amplifier operating at 2.45 GHz, in the S-band frequency. The Cree's CG2H40045F GaN HEMT (High Electron Mobility Transistor) is used for this design. The Gallium Nitride (GaN) technology has been chosen in light of its advantageous properties such as high breakdown voltage, high band gap, as well as high thermal conditions. The paper investigates the different design trade-offs for finding a good balance between various key parameters of the PA (linearity, efficiency, and gain). A design approach has been proposed and the microstrip lines based on the Smith Chart tool available in ADS software have been used for the matching process. The class AB was selected to reach a good agreement between linearity and efficiency, provided by this class. After various process applications from DC characterization to simulations, the proposed design achieves a power added efficiency more than 50% at power saturation with a gain of 15 dB in schematic simulation. The layout dimensions are 55.5 × 64.45 mm 2 on PCB technology.
功率放大器(PA)等高性能电子器件对无线通信非常重要。本文提出了一种工作频率为2.45 GHz的s波段AB类功率放大器的设计方案。该设计使用Cree的CG2H40045F GaN HEMT(高电子迁移率晶体管)。氮化镓(GaN)技术具有高击穿电压、高带隙和高热条件等优点。本文研究了不同的设计权衡，以找到PA的各种关键参数(线性度，效率和增益)之间的良好平衡。提出了一种设计方法，并利用ADS软件中的史密斯图工具绘制微带线进行匹配。选择AB级是为了在线性度和效率之间达到很好的一致性，这是AB级提供的。经过从直流表征到仿真的各种工艺应用，所提出的设计在功率饱和时的功率增加效率超过50%，原理图仿真的增益为15 dB。PCB工艺上的布局尺寸为55.5 × 64.45 mm2。
{"title":"GaN HEMT power amplifier design for 2.45 GHz wireless applications","authors":"Paula Akossiwa Atchike;Jamal Zbitou;Ahmed El Oualkadi;Pascal Dherbécourt","doi":"10.23919/SAIEE.2023.10319379","DOIUrl":"https://doi.org/10.23919/SAIEE.2023.10319379","url":null,"abstract":"Electronic devices with high performances like Power Amplifiers (PA) are very important for Wireless communications. This paper proposes a design of a class AB power amplifier operating at 2.45 GHz, in the S-band frequency. The Cree's CG2H40045F GaN HEMT (High Electron Mobility Transistor) is used for this design. The Gallium Nitride (GaN) technology has been chosen in light of its advantageous properties such as high breakdown voltage, high band gap, as well as high thermal conditions. The paper investigates the different design trade-offs for finding a good balance between various key parameters of the PA (linearity, efficiency, and gain). A design approach has been proposed and the microstrip lines based on the Smith Chart tool available in ADS software have been used for the matching process. The class AB was selected to reach a good agreement between linearity and efficiency, provided by this class. After various process applications from DC characterization to simulations, the proposed design achieves a power added efficiency more than 50% at power saturation with a gain of 15 dB in schematic simulation. The layout dimensions are 55.5 × 64.45 mm\u0000<sup>2</sup>\u0000 on PCB technology.","PeriodicalId":42493,"journal":{"name":"SAIEE Africa Research Journal","volume":"114 4","pages":"106-113"},"PeriodicalIF":1.4,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10319379","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138138385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-09DOI: 10.23919/SAIEE.2023.10214184
{"title":"Editors and reviewers","authors":"","doi":"10.23919/SAIEE.2023.10214184","DOIUrl":"https://doi.org/10.23919/SAIEE.2023.10214184","url":null,"abstract":"","PeriodicalId":42493,"journal":{"name":"SAIEE Africa Research Journal","volume":"114 3","pages":"70-70"},"PeriodicalIF":1.4,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/8475037/10214182/10214184.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67845945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-09DOI: 10.23919/SAIEE.2023.10214186
Casey J. Bryant;P. Gideon Wiid
This article describes an antenna characterization measurement technique that can be achieved using low-cost equipment on a sports field. It is an adaptation of a reflection range measurement and results were compared to control measurements done at an open-area-test-site as well as in an anechoic chamber. This technique was capable of obtaining results with accuracy to within 2 dB for boresight gain and within 2 dB for the main beam of the antenna pattern. Its purpose is not to be highly accurate, but rather to show that it is possible to cost-sensitively introduce students to radio frequency equipment, as well as have access to a pre-characterization test method for inhouse, student-built antennas at tertiary education institutions.
{"title":"A cost-sensitive technique to pre-characterize UHF antennas at tertiary education institutions","authors":"Casey J. Bryant;P. Gideon Wiid","doi":"10.23919/SAIEE.2023.10214186","DOIUrl":"10.23919/SAIEE.2023.10214186","url":null,"abstract":"This article describes an antenna characterization measurement technique that can be achieved using low-cost equipment on a sports field. It is an adaptation of a reflection range measurement and results were compared to control measurements done at an open-area-test-site as well as in an anechoic chamber. This technique was capable of obtaining results with accuracy to within 2 dB for boresight gain and within 2 dB for the main beam of the antenna pattern. Its purpose is not to be highly accurate, but rather to show that it is possible to cost-sensitively introduce students to radio frequency equipment, as well as have access to a pre-characterization test method for inhouse, student-built antennas at tertiary education institutions.","PeriodicalId":42493,"journal":{"name":"SAIEE Africa Research Journal","volume":"114 3","pages":"72-79"},"PeriodicalIF":1.4,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/8475037/10214182/10214186.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44684305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-09DOI: 10.23919/SAIEE.2023.10214228
Samantha Woods;Callen Fisher
Thumb loss can diminish one's hand's functionality by up to 40% and the loss of one's entire hand can severely impact a person's ability to perform simple day-to-day tasks. Therefore, there exists a need to focus on the development of a thumb mechanism which supports dexterous grasping activities in anthropomorphic robotic hands. This paper documents the design process of a novel robotic hand, and shows experimental results validating its overall performance. A large focus was placed on developing a novel thumb mechanism which could replicate the thumb's characteristic movement types, namely flexion-extension, abduction-adduction, and oppositionreposition. Additional focus was placed on developing a mechanism for flexion-extension movement of the fingers which did not incorporate passive components and on producing a fully self-contained prototype — with the electronics and actuators contained inside the palm, and the power supply inset against the back of the palm. The hand successfully followed motion commands from a sensor glove, and was able to replicate 14 grasp configurations which demonstrated its dexterous grasping abilities.
{"title":"Development of a self-contained robotic hand with dexterous grasping capabilities for research applications","authors":"Samantha Woods;Callen Fisher","doi":"10.23919/SAIEE.2023.10214228","DOIUrl":"10.23919/SAIEE.2023.10214228","url":null,"abstract":"Thumb loss can diminish one's hand's functionality by up to 40% and the loss of one's entire hand can severely impact a person's ability to perform simple day-to-day tasks. Therefore, there exists a need to focus on the development of a thumb mechanism which supports dexterous grasping activities in anthropomorphic robotic hands. This paper documents the design process of a novel robotic hand, and shows experimental results validating its overall performance. A large focus was placed on developing a novel thumb mechanism which could replicate the thumb's characteristic movement types, namely flexion-extension, abduction-adduction, and oppositionreposition. Additional focus was placed on developing a mechanism for flexion-extension movement of the fingers which did not incorporate passive components and on producing a fully self-contained prototype — with the electronics and actuators contained inside the palm, and the power supply inset against the back of the palm. The hand successfully followed motion commands from a sensor glove, and was able to replicate 14 grasp configurations which demonstrated its dexterous grasping abilities.","PeriodicalId":42493,"journal":{"name":"SAIEE Africa Research Journal","volume":"114 3","pages":"87-92"},"PeriodicalIF":1.4,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/8475037/10214182/10214228.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42831271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-09DOI: 10.23919/SAIEE.2023.10214227
Callen Fisher;Dean Pretorius;Nathan Weiss
Humans and animals leverage agility to negotiate the unpredictable environments we occupy. In order for legged robots to leave sterile lab environments, they need to be agile enough to negotiate our lives. Currently, human agility is far superior to the state-of-the-art robotic platforms. Replicating this on robotic platforms require a profound understanding of how contact events are leveraged to complete agile tasks. In line with this aim, this letter was an initial investigation into bipedal turning, to gain insight into how turning was achieved, and to identify any kinematic trends that emerged from the optimization results. This research was conducted on a simulated 10 DoF non-planar bipedal platform with point feet, and made use of a realistic friction cone, and not a linearized approximation. The mathematical model used was based on the bipedal robot currently under development. Two experiments were conducted: rapid turns with a fixed turn angle at varying speeds, and rapid turns with varying turn angles at a fixed speed. Results indicated that slip occurred 93.32% of the contact duration, and turn overshoot was present in all trajectories analyzed. Additionally, a long-time-horizon trajectory was presented to motivate the feasibility and stability of the turn trajectories studied.
{"title":"Initial investigation into bipedal turning: A trajectory optimization study","authors":"Callen Fisher;Dean Pretorius;Nathan Weiss","doi":"10.23919/SAIEE.2023.10214227","DOIUrl":"10.23919/SAIEE.2023.10214227","url":null,"abstract":"Humans and animals leverage agility to negotiate the unpredictable environments we occupy. In order for legged robots to leave sterile lab environments, they need to be agile enough to negotiate our lives. Currently, human agility is far superior to the state-of-the-art robotic platforms. Replicating this on robotic platforms require a profound understanding of how contact events are leveraged to complete agile tasks. In line with this aim, this letter was an initial investigation into bipedal turning, to gain insight into how turning was achieved, and to identify any kinematic trends that emerged from the optimization results. This research was conducted on a simulated 10 DoF non-planar bipedal platform with point feet, and made use of a realistic friction cone, and not a linearized approximation. The mathematical model used was based on the bipedal robot currently under development. Two experiments were conducted: rapid turns with a fixed turn angle at varying speeds, and rapid turns with varying turn angles at a fixed speed. Results indicated that slip occurred 93.32% of the contact duration, and turn overshoot was present in all trajectories analyzed. Additionally, a long-time-horizon trajectory was presented to motivate the feasibility and stability of the turn trajectories studied.","PeriodicalId":42493,"journal":{"name":"SAIEE Africa Research Journal","volume":"114 3","pages":"80-86"},"PeriodicalIF":1.4,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/8475037/10214182/10214227.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45594063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-09DOI: 10.23919/SAIEE.2023.10214229
{"title":"Notes for authors","authors":"","doi":"10.23919/SAIEE.2023.10214229","DOIUrl":"https://doi.org/10.23919/SAIEE.2023.10214229","url":null,"abstract":"","PeriodicalId":42493,"journal":{"name":"SAIEE Africa Research Journal","volume":"114 3","pages":"93-93"},"PeriodicalIF":1.4,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/8475037/10214182/10214229.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67845942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-15DOI: 10.23919/SAIEE.2023.10071977
Shingirirai Chakoma;Philip Baron
There is a significant population of hearing-impaired people who reside in South Africa; however, South African Sign Language (SASL) has not yet been recognized as South Africa's 12 th official language, resulting in slow uptake of this important language. Since most people do not know SASL, there is a need for gesture recognition systems that convert Sign Language (SL) to verbal and/or text to reduce the communication barriers between the hearing and the hearing-impaired. This study presents an application for gesture recognition in converting SASL to both a verbal format and a textual format. By using gesture recognition from a single wearable glove, hand gestures were quantified, categorized, and then converted into an auditory format and played on a speaker, as well as the equivalent textual information displayed on an LCD screen. The complete prototype consists of a wearable glove with a transmitter and an associated receiver box which were all designed to cost less than $150. The glove consists of five flex sensors that measure the handshape and an inertial measurement unit which measures the hand motion. The handshape and motion data are processed and wirelessly transmitted to a receiver box. This then displays the associated English character on an LCD while also playing the audio on a speaker. The SL converter can convert the 26 letters of the SASL manual alphabet with an overall accuracy of 69%, It can also convert common words and phrases, as well as proper names when fingerspelled.
{"title":"Converting South African sign language to verbal","authors":"Shingirirai Chakoma;Philip Baron","doi":"10.23919/SAIEE.2023.10071977","DOIUrl":"10.23919/SAIEE.2023.10071977","url":null,"abstract":"There is a significant population of hearing-impaired people who reside in South Africa; however, South African Sign Language (SASL) has not yet been recognized as South Africa's 12\u0000<sup>th</sup>\u0000 official language, resulting in slow uptake of this important language. Since most people do not know SASL, there is a need for gesture recognition systems that convert Sign Language (SL) to verbal and/or text to reduce the communication barriers between the hearing and the hearing-impaired. This study presents an application for gesture recognition in converting SASL to both a verbal format and a textual format. By using gesture recognition from a single wearable glove, hand gestures were quantified, categorized, and then converted into an auditory format and played on a speaker, as well as the equivalent textual information displayed on an LCD screen. The complete prototype consists of a wearable glove with a transmitter and an associated receiver box which were all designed to cost less than $150. The glove consists of five flex sensors that measure the handshape and an inertial measurement unit which measures the hand motion. The handshape and motion data are processed and wirelessly transmitted to a receiver box. This then displays the associated English character on an LCD while also playing the audio on a speaker. The SL converter can convert the 26 letters of the SASL manual alphabet with an overall accuracy of 69%, It can also convert common words and phrases, as well as proper names when fingerspelled.","PeriodicalId":42493,"journal":{"name":"SAIEE Africa Research Journal","volume":"114 2","pages":"49-57"},"PeriodicalIF":1.4,"publicationDate":"2023-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/8475037/10071972/10071977.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47841482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-15DOI: 10.23919/SAIEE.2023.10071974
{"title":"Editors and reviewers","authors":"","doi":"10.23919/SAIEE.2023.10071974","DOIUrl":"https://doi.org/10.23919/SAIEE.2023.10071974","url":null,"abstract":"","PeriodicalId":42493,"journal":{"name":"SAIEE Africa Research Journal","volume":"114 2","pages":"38-38"},"PeriodicalIF":1.4,"publicationDate":"2023-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/8475037/10071972/10071974.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67968042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-15DOI: 10.23919/SAIEE.2023.10071976
Ali Ziryawulawo;Melissa Kirabo;Cosmas Mwikirize;Jonathan Serugunda;Edwin Mugume;Simon Peter Miyingo
With the ever-growing traffic density, the number of road accidents has continued to increase. Finding solutions to reduce road accidents and improve traffic safety has become a top priority for Kiira Motors Corporation, a Ugandan state-owned automotive company. The company seeks to develop intelligent driver assistance systems for its market entry product, the Kayoola EVS bus. A machine learning-based driver monitoring system that would monitor driver drowsiness and send out an alarm in case drowsiness is detected has been developed in an attempt to reduce drowsiness-related accidents. The system consists of a camera positioned in such a way as to keep track of the driver's face. The camera is interfaced with a Raspberry Pi minicomputer which carries out the computations and analysis and when drowsiness is detected, an alarm is triggered. Dangerous driver behavior including distraction and fatigue has long been recognized as the main contributing factor in traffic accidents. This paper therefore presents the development of a driver monitoring system for the Kayoola Electric City Bus to address the increasing occurrences of road accidents. The machine learning-based driver monitoring system is designed to be non-intrusive with continuous real-time operation.
{"title":"Machine learning based driver monitoring system: A case study for the Kayoola EVS","authors":"Ali Ziryawulawo;Melissa Kirabo;Cosmas Mwikirize;Jonathan Serugunda;Edwin Mugume;Simon Peter Miyingo","doi":"10.23919/SAIEE.2023.10071976","DOIUrl":"10.23919/SAIEE.2023.10071976","url":null,"abstract":"With the ever-growing traffic density, the number of road accidents has continued to increase. Finding solutions to reduce road accidents and improve traffic safety has become a top priority for Kiira Motors Corporation, a Ugandan state-owned automotive company. The company seeks to develop intelligent driver assistance systems for its market entry product, the Kayoola EVS bus. A machine learning-based driver monitoring system that would monitor driver drowsiness and send out an alarm in case drowsiness is detected has been developed in an attempt to reduce drowsiness-related accidents. The system consists of a camera positioned in such a way as to keep track of the driver's face. The camera is interfaced with a Raspberry Pi minicomputer which carries out the computations and analysis and when drowsiness is detected, an alarm is triggered. Dangerous driver behavior including distraction and fatigue has long been recognized as the main contributing factor in traffic accidents. This paper therefore presents the development of a driver monitoring system for the Kayoola Electric City Bus to address the increasing occurrences of road accidents. The machine learning-based driver monitoring system is designed to be non-intrusive with continuous real-time operation.","PeriodicalId":42493,"journal":{"name":"SAIEE Africa Research Journal","volume":"114 2","pages":"40-48"},"PeriodicalIF":1.4,"publicationDate":"2023-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/8475037/10071972/10071976.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47391089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-15DOI: 10.23919/SAIEE.2023.10071979
{"title":"Notes for authors","authors":"","doi":"10.23919/SAIEE.2023.10071979","DOIUrl":"https://doi.org/10.23919/SAIEE.2023.10071979","url":null,"abstract":"","PeriodicalId":42493,"journal":{"name":"SAIEE Africa Research Journal","volume":"114 2","pages":"67-67"},"PeriodicalIF":1.4,"publicationDate":"2023-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/8475037/10071972/10071979.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67967852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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